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Open Access Research

Is routine karyotyping required in prenatal samples with a molecular or metabolic referral?

Angelique JA Kooper1*, Jacqueline JPM Pieters2, Brigitte HW Faas1, Lies H Hoefsloot1, Ineke van der Burgt1, Hans A Zondervan3 and Arie PT Smits1

Author Affiliations

1 Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands

2 Department of Obstetrics and Gynaecology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands

3 Obstetrics and Gynaecology, Rijnstate Hospital Arnhem, the Netherlands

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Molecular Cytogenetics 2012, 5:7  doi:10.1186/1755-8166-5-7

Published: 27 January 2012

Abstract

As a routine, karyotyping of invasive prenatal samples is performed as an adjunct to referrals for DNA mutation detection and metabolic testing. We performed a retrospective study on 500 samples to assess the diagnostic value of this procedure. These samples included 454 (90.8%) chorionic villus (CV) and 46 (9.2%) amniocenteses specimens. For CV samples karyotyping was based on analyses of both short-term culture (STC) and long-term culture (LTC) cells. Overall, 19 (3.8%) abnormal karyotypes were denoted: four with a common aneuploidy (trisomy 21, 18 and 13), two with a sex chromosomal aneuploidy (Klinefelter syndrome), one with a sex chromosome mosaicism and twelve with various autosome mosaicisms. In four cases a second invasive test was performed because of an abnormal finding in the STC. Taken together, we conclude that STC and LTC karyotyping has resulted in a diagnostic yield of 19 (3.8%) abnormal cases, including 12 cases (2.4%) with an uncertain significance. From a diagnostic point of view, it is desirable to limit uncertain test results as secondary test findings. Therefore, we recommend a more targeted assay, such as e.g. QF-PCR, as a replacement of the STC and to provide parents the autonomy to choose between karyotyping and QF-PCR.

Keywords:
DNA diagnostics; karyotyping; mutation detection; QF-PCR; rapid aneuploidy test; prenatal diagnosis